1. Field of the Invention
A method of measuring a 3D shape, which can measure 3D shape of target objects on a circuit board by searching a database for information on the bare board (the circuit board with no components mounted thereon) when the inspection option is set to the teaching-based inspection mode or by performing bare board teaching when the circuit board being inspected is from a supplier for which there is no bare board information.
2. Description of the Related Art
FIG. 1 is a flowchart illustrating a method of measuring a 3D shape according to the conventional art. Referring to FIG. 1, to measure a 3D shape of an object, in operation S10, an illuminated grating pattern is emitted towards a reference surface by emitting a light generated from an illumination source (not shown) towards a grating device (not shown) to acquire a reference phase corresponding to a reference surface. In operation S11, the grating is moved in a fine pitch increments using a piezoelectric actuator (not shown) and emitted towards the reference surface and a grating pattern image is acquired using a charged coupled device (CCD) camera and a frame grabber (not shown). In operation S12, when the grating pattern image is acquired by the frame grabber, a bucket algorithm is applied to the grating pattern image. In operation S13, the reference phase with respect to the reference surface is acquired.
In operation S15, when the reference phase corresponding to the reference surface is acquired, an object to be measured is placed on a moving table and a light generated from the illumination source is emitted towards a surface being measured of the object to be measured to acquire a phase of the object to be measured. In operation S16, the grating is moved by a fine increment using the piezoelectric actuator to apply the bucket algorithm, and the grating pattern image reflected from the surface being measured is acquired via the CCD camera and the frame grabber. In operation S17, the bucket algorithm is applied to the grating pattern image. In operation S18, an object phase of the object being measured is acquired.
When the object phase is acquired, the object phase is subtracted from the reference phase in operation S20, and a moire phase is acquired in operation S21. When the moire phase is acquired, the moire phase is unwrapped in operation S22, and actual height information of the object being measured is acquired by using a result of the unwrapping. Through the above-described operations, the 3D shape of the object being measured is acquired.
However, the conventional 3D shape measuring method has a problem in that since each of the measuring conditions is manually calculated and then the measurement is performed, when there is a totally new object being measured, the operator becomes tired and then less productive.